1. Field of the Invention
The present invention relates to easily conveyable and easily meterable mixtures of aromatic oils and phenylenediamines having high stability in storage as well as the use thereof in the production of rubbers and rubber articles.
2. Description of the Prior Art
The use of phenylenediamines in the production of rubbers and rubber articles is known (see Hofmann, Rubber Technology Handbook, Houser Publishers, 1989, page 268 ff.). The phenylenediamines to be used for the rubber application, which are in the form of solids or viscous melts at room temperature, are generally sold, stored, metered and transported in the form of solids at room temperature or in the form of liquid melts at more elevated temperatures (up to 100.degree. C.). Handling these substances in the form of a liquid melt has the advantage over handling in granular form that melts are dust-free, have a higher density than that of a bed of granules, are capable of being pumped and can therefore be mixed and metered more efficiently.
A disadvantage of handling phenylenediamines in the form of low-viscosity melts is the energy consumption and the technical expense which are necessary for the transport and storage of the hot melt. Especially during metering and passage to the mixing apparatus, it is necessary to heat the entire system of ducts because the product instantly crystallises out on being cooled to below the melting temperature and consequently clogs the ducts.
The use of aromatic mineral oils in the production of rubbers and rubber articles is also known (see Hofmann, Rubber Technology Handbook, Houser Publishers, 1989, page 296 ff.).
The aromatic oils used in the process are generally highly viscous and, in order to lower the viscosity, they are often stored, metered and admixed to the rubber-mixtures at elevated temperatures.
It was accordingly the object of the present invention to provide the aromatic oils and the phenylenediamines in an easily transportable and easily meterable form which moreover has a high stability in storage.
This object was fulfilled by the provision of the mixtures of aromatic oils and phenylenediamines according to the invention.